1. Real Time Tasks :
i) It is a task in which performance is judged on the basis of time. It means computation is correct only if it has produced its correct output within specified time constrained.
Correct Result = Correct time + Within Specified time
ii) Failure to time constraint is designated either as system failure or reduced value of quality of service
Following are the examples with real - time tasks are -
- Robotics
- Air traffic control
- Weapon guidance system
- Telecommunications
- Medical diagnostic & life support systems
- Anti - lock banking system
- Real time database
In all the above applications time is important parameter. Eg. In Air traffic control, aircraft are guided accurately for landing & navigation. Any delay in response will result in disaster in terms of human life.0
1.1 Real Time Video / Speech Processing
i) A moving picture or speech sample of 1 second is processed in 1 second makes real time processing. If it takes more than 1 second then it is not a real time processing.
1.2 Are Real time and Embedded systems same?
i) No. Embedded systems are designed for specific set of applications. When such system requires time constraint operation, it becomes real time embedded system.
ii) All embedded systems are not real time. For Eg Printer is example of embedded system but it not a real time where as Robot is an exaple of real time.
Terms :
1. Ready Time
Time instance at which task is ready for execution.
2. Scheduling Time
Time instance at which task gets chance to execute.
3. Completion Time
This is time at which task completes its execution.
4. Deadline
This is instant of time by which execution of the task should be completed.
5. Run Time
Time taken to complete the task without any interruption.
6. Tardiness
Amount of time by which a task misses the deadline. It is difference between completion time instance and deadline.
7. Laxity
Laxity of task is maximum amount of time it can wait & still meet its deadline.
i) It is a task in which performance is judged on the basis of time. It means computation is correct only if it has produced its correct output within specified time constrained.
Correct Result = Correct time + Within Specified time
ii) Failure to time constraint is designated either as system failure or reduced value of quality of service
Following are the examples with real - time tasks are -
- Robotics
- Air traffic control
- Weapon guidance system
- Telecommunications
- Medical diagnostic & life support systems
- Anti - lock banking system
- Real time database
In all the above applications time is important parameter. Eg. In Air traffic control, aircraft are guided accurately for landing & navigation. Any delay in response will result in disaster in terms of human life.0
1.1 Real Time Video / Speech Processing
i) A moving picture or speech sample of 1 second is processed in 1 second makes real time processing. If it takes more than 1 second then it is not a real time processing.
1.2 Are Real time and Embedded systems same?
i) No. Embedded systems are designed for specific set of applications. When such system requires time constraint operation, it becomes real time embedded system.
ii) All embedded systems are not real time. For Eg Printer is example of embedded system but it not a real time where as Robot is an exaple of real time.
Terms :
1. Ready Time
Time instance at which task is ready for execution.
2. Scheduling Time
Time instance at which task gets chance to execute.
3. Completion Time
This is time at which task completes its execution.
4. Deadline
This is instant of time by which execution of the task should be completed.
5. Run Time
Time taken to complete the task without any interruption.
6. Tardiness
Amount of time by which a task misses the deadline. It is difference between completion time instance and deadline.
7. Laxity
Laxity of task is maximum amount of time it can wait & still meet its deadline.
